AVO began in 1923 as the Automatic Coil Winder and Electrical Company Ltd (ACWEECO). This company began as a manufacturer of coil winding machines, but soon branched out into test equipment with a multi range test meter designed by D Macadie. This instrument was to become the Avo meter and is thought to be the first instrument to measure amperes, volts and ohms, a facility that gave the instrument, and later the company, its name. In 1930, as demand for their products increased, the company moved from its original premises in Rochester Row to a larger factory on Vauxhall Bridge Road, where the first Universal Avo meter was produced. The company also began to branch out into other test equipment and developed the "Avominor" and a range of valve testers.

In 1957, the company's name was changed to AVO Ltd. It acquired Taylor Instruments the following year, and then joined the Metal Industries Group (MIG). With the growing expansion of the company, it was decided to built an entirely new plant with office accommodation in Dover, where the company moved in 1966. The company was acquired by Thorn Electrical Industries in 1967 as part of its takeover of the Metal Industries Group, but remained at the Dover site.

Other companies joined AVO at Dover as they were acquired by Thorn, including Foster Transformers, Evershed and Vignoles (Megger Instruments), H W Sullivan and Record. Thorn then merged with EMI Ltd to form Thorn EMI in 1980 and then, in 1982, merged the instrument companies at Dover to form Thorn EMI Instruments Ltd.

This section of Thorn EMI was bought out by its management in 1987 and renamed Megger Instruments Ltd. In 1991 it was bought by TBG and in 1994 it was renamed Avo International Ltd.


ACWAEEC, (Automatic Coil Winder And Electrical Equipment Company)
Avo meter Model B
Selenium sensor
Year: 1936
reflected light


Note: Inventor of this meter is Hugh Sutherland Macadie for the 'Automatic Coil Winder And Electrical Equipment Company.' The application date for patent was on march 20th. 1936.

Revised version of Avo's second model from 1938. The patent has now been issued, and the calculator ring has been improved

Buying stuff on ebay always has more or less a risc. Twice I have send a meter back because what I received was a piece of junk and in no way according the description. Not only I send the meter back but also I gave those sellers a really bad feedback. Also sometimes you will receive a meter that is according the description but of a very low quality and than there are the meters tampered with by really untrained people!

So also this AVO meter, not working, the glass in the front broken, the needle fixed for ever in the corner and the screen from the scale was really bad. After opening I saw that here also a plumber has been working on this meter. So after a few hours of work we again have a working meter, looking much better than the one I received.

The Selenium cell is made by Electrocell dated 26 FEB 1938

The construction of the meter is very simple, 1 connection is made to the coil on the meter and the other to the iron core. The copper piece is making contact to the iron core and also to the selenium sensor. The copper frame ob the front of the sensor is making contact with the other side of the sensor and by a wire connected to the coil on top of the core.


Another point is the manufacturing of the meter. It seems the made the brass hood of the meter a bit to small. because of this you can see the cracks in the 4 corners of the meter. It seems they went wrong with the dimensions somewhere. I vae noticed this problem with more meters.


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